Preclinical evaluation of the sirolimus-eluting iron bioresorbable scaffold in canine below-the-knee artery.

Background and aims: Infrapopliteal artery intervention has yielded suboptimal results in below-the-knee (BTK) arterial disease. However, bioresorbable scaffolds are a potential treatment for this condition. This study compared the support performance, anti-hyperplastic effects, and histological manifestations between a sirolimus-eluting iron bioresorbable scaffold (IBS) and an everolimus-eluting stent (EES) within 6 months and the corrosion profile during 12 months in canine BTK arteries.

Methods: Eighteen IBS and twelve EES systems were implanted into nonatherosclerotic BTK arteries in dogs. Support performance and inhibit intimal hyperplasia, histological manifestations, and the corrosion profile were compared between the two systems using angiography, optical coherence tomography (OCT), micro-computed tomography, and histopathologic evaluation at 1, 3, 6, and 12 months.

Results: All systems were successfully implanted. There was no significant difference in the area of stenosis between the IBS and EES groups within 6 months. Semi-quantitative OCT revealed degradation of the IBS at 3 months, with strut corrosion rates of 24.6 %, 45.0 %, and 69.2 % at 3, 6, and 12 months. Micro-computed tomography showed that the IBS maintained its integrity at 1 month without corrosion, with more struts fractured because of degradation at 6 and 12 months. Endothelialization was complete at 1 month in both groups. There was no significant between-group difference in cell responses during 6 months of follow-up, with the exception of macrophages.

Conclusion: This preclinical study suggests that the IBS has performance support, anti-hyperplastic effects, and histological manifestations comparable to those of the EES within 6 months, with a reasonable corrosion profile over 12 months.